WO2012114745A1

WO2012114745A1 - Compound containing substituted triphenyle ring structure, and organic electroluminescent element

Info

Publication number: WO2012114745A1
Application number: PCT/JP2012/001217
Authority: WO
Inventors: 安達　千波矢; 和法富樫; 紀昌横山; 真太朗野村
Original assignee: 保土谷化学工業株式会社; 国立大学法人九州大学
Priority date: 2011-02-23
Filing date: 2012-02-23
Publication date: 2012-08-30
Also published as: CN103402981A; US20170338417A1; US9685612B2; JPWO2012114745A1; EP2679581A4; JP5453621B2; US10797242B2; TWI508958B; US10026903B2; KR20140047592A; JP2014088399A; US20170271595A1; EP2679581A1; US20140034936A1; JP5861843B2; EP2679581B1; KR101975067B1; TW201240989A; EP3255040A1

Abstract

Provided is an organic compound having excellent properties for electron injection and transportation performance as a material for an organic electroluminescent element with low power consumption. Additionally provided using this compound is an organic electroluminescent element with low power consumption. The present invention is a compound containing substituted bipyridyl groups and a triphenyle ring structure represented in general formula (1) and (2). The present invention is an organic electroluminescent element having a pair of electrodes, and at least one organic layer interposed therebetween, characterized in that the compound is used as a constituent material for at least one organic layer.

Description

Compound having substituted triphenylene ring structure and organic electroluminescence device

The present invention relates to a compound suitable for an organic electroluminescence element (hereinafter abbreviated as an organic EL element) which is a self-luminous element suitable for various display devices and the element, and more specifically, a substituted bipyridyl group. And a compound having a triphenylene ring structure, and an organic EL device using the compound.

Since organic EL elements are self-luminous elements, they have been actively researched because they are brighter and more visible than liquid crystal elements and are capable of clear display.

In 1987, Eastman Kodak's C.I. W. Tang et al. Have made a practical organic EL device using an organic material by developing a laminated structure device in which various roles are assigned to each material. They laminate a phosphor capable of transporting electrons and an organic substance capable of transporting holes, and inject both charges into the phosphor layer to emit light. A high luminance of 1000 cd / m ² or more was obtained (see, for example, Patent Document 1 and Patent Document 2).

To date, many improvements have been made for practical application of organic EL devices, and various roles have been further subdivided, and sequentially on the substrate, anode, hole injection layer, hole transport layer, light emitting layer, electron transport High efficiency and durability are achieved by an electroluminescent element provided with a layer, an electron injection layer, and a cathode (see, for example, Non-Patent Document 1).

Also, the use of triplet excitons has been attempted for the purpose of further improving the luminous efficiency, and the use of phosphorescent emitters has been studied (for example, see Non-Patent Document 2).

The light emitting layer can also be prepared by doping a charge transporting compound generally called a host material with a phosphor or a phosphorescent light emitter. As described in Non-Patent Documents 1 and 2 above, selection of an organic material in an organic EL element greatly affects various characteristics such as efficiency and durability of the element.

In the organic EL element, the light injected from both electrodes is recombined in the light emitting layer to obtain light emission. However, since the hole moving speed is faster than the electron moving speed, some of the holes pass through the light emitting layer. There is a problem of efficiency reduction due to passing through. Therefore, an electron transport material having a high electron moving speed is demanded.

Tris (8-hydroxyquinoline) aluminum (hereinafter abbreviated as Alq ₃ ), which is a typical luminescent material, is generally used as an electron transport material, but has a slow electron mobility and a work function of 5. Since it is 6 eV, it cannot be said that the hole blocking performance is sufficient.

A method for preventing a part of holes from passing through the light emitting layer and improving the probability of charge recombination in the light emitting layer is to insert a hole blocking layer. As a hole blocking material, triazole derivatives (for example, refer to Patent Document 3), bathocuproine (hereinafter abbreviated as BCP), mixed ligand complexes of aluminum [aluminum (III) bis (2-methyl-8) -Quinolinato) -4-phenylphenolate (hereinafter abbreviated as BAlq)] (for example, see Non-Patent Document 2).

On the other hand, 3- (4-biphenylyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4-triazole (hereinafter abbreviated as TAZ) is used as an electron transport material having excellent hole blocking properties. Have been proposed (see, for example, Patent Document 3).

Since TAZ has a large work function of 6.6 eV and high hole blocking ability, an electron transporting hole blocking layer laminated on the cathode side of a fluorescent light emitting layer or phosphorescent light emitting layer produced by vacuum deposition or coating. And contributes to high efficiency of the organic EL element (see, for example, Non-Patent Document 3).

However, low electron transportability is a major problem in TAZ, and it is necessary to produce an organic EL element in combination with an electron transport material with higher electron transportability (see, for example, Non-Patent Document 4). .

BCP also has a high work function of 6.7 eV and a high hole blocking ability, but its glass transition point (Tg) is as low as 83 ° C., so that the stability of the thin film is poor and it functions sufficiently as a hole blocking layer. I can't say that. Therefore, it has been proposed to use BAlq as a hole blocking layer as a measure for extending the lifetime of phosphorescent light emitting devices. In this device, although the life extension is improved, since the work function of BAlq is as small as 5.8 eV, the holes are not efficiently confined in the light emitting layer, and the efficiency is reduced as compared with the device using BCP. Seen, not enough.

None of the materials has sufficient film stability or a function of blocking holes. In order to improve the device characteristics of an organic EL device, an organic compound having excellent electron injection / transport performance and hole blocking capability and high stability in a thin film state is required.

As compounds improved from these, compounds having an anthracene ring structure and a benzimidazole ring structure have been proposed (see, for example, Patent Document 4).

However, in devices using these compounds in the electron injection layer and / or the electron transport layer, although the light emission efficiency has been improved, it is still not sufficient, and the drive voltage is lowered and the light emission efficiency is further increased. In particular, high power efficiency is required.

JP-A-8-048656 Japanese Patent No. 3194657 Japanese Patent No. 2734341 WO2003 / 060956

An object of the present invention is to provide an organic compound having characteristics excellent in electron injection / transport performance as a material for a low power consumption organic EL element, and further using this compound, a low power consumption organic EL element Is to provide.

The physical properties that the organic compound to be provided by the present invention should have include (1) good electron injection properties, (2) fast electron transfer speed, and (3) high molecular orientation. And (4) excellent heat resistance. In addition, the physical characteristics that the organic EL element to be provided by the present invention should have include (1) high power efficiency, (2) low light emission starting voltage, and (3) low practical driving voltage. I can give you something.

Therefore, in order to achieve the above object, the present inventors have high flatness, that is, good intermolecular packing in a thin film state can be expected, and good electron transportability is expected due to the abundance of π electrons. Designed and chemically synthesized a compound that combines a triphenylene ring structure that can be formed and a bipyridyl group with high planarity and high electron affinity, and prototyped various organic EL devices using the compound, and conducted rigorous evaluation of device characteristics As a result, the present invention has been completed.

That is, the present invention is a compound having a substituted bipyridyl group represented by the general formula (1) or (2) and a triphenylene ring structure.

(1)

(Wherein R ₁ to R ₁₈ may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or an optionally substituted carbon atom) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n1 and n2 may be the same or different and each represents 2 or 3. Here, a plurality of R ₃ to R ₈ may be the same or different from each other.

(2)

(Wherein R ₁₉ to R ₃₉ may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or a carbon atom which may have a substituent) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n3, n4 and n5 may be the same or different and each represents 2 or 3. Here, a plurality of R ₂₂ to R ₃₀ may be the same or different from each other.

The present invention is also a compound having a substituted bipyridyl group and a triphenylene ring structure represented by the following general formula (1 ').

(1 ')

In addition, the present invention is a compound having a substituted bipyridyl group represented by the following general formula (1 ″) and a triphenylene ring structure.

(1 '')

Further, the present invention is a compound having a substituted bipyridyl group represented by the following general formula (1 ′ ″) and a triphenylene ring structure.

(1 ''')

(In the formula, R ₃ to R ₁₈ and R ₄₀ to R ₄₇ may be the same or different and have a hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, trifluoromethyl group, or substituent. A linear or branched alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycycle Represents an aromatic group.)

Further, the present invention is a compound having a substituted bipyridyl group and a triphenylene ring structure represented by the following general formula (1 '' '' ').

(1 '''')

Further, the present invention is a compound having a substituted bipyridyl group and a triphenylene ring structure represented by the following general formula (2 ').

(2 ')

Further, the present invention provides an organic EL device having a pair of electrodes and at least one organic layer sandwiched therebetween, wherein at least one of the organic layers is represented by the general formula (1) to the general formula (1 ″ ″), An organic EL device comprising a compound having a substituted bipyridyl group represented by the general formula (2) or the general formula (2 ′) and a triphenylene ring structure.

“Optionally substituted carbon” represented by R ₁ to R ₄₇ in general formula (1) to general formula (1 ″ ″), general formula (2), or general formula (2 ′) As the “alkyl group” in the “straight or branched alkyl group having 1 to 6 atoms”, specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, Examples thereof include a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, and an n-hexyl group.

The number of carbon atoms having a substituent is 1 to 6 represented by R ₁ to R ₄₇ in the general formula (1) to the general formula (1 ″ ″), the general formula (2), or the general formula (2 ′). Specific examples of the “substituent” in the “straight-chain or branched alkyl group” include a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, a straight-chain group having 1 to 6 carbon atoms or Branched alkyl group, cyclopentyl group, cyclohexyl group, dialkylamino group substituted with linear or branched alkyl group having 1 to 6 carbon atoms, phenyl group, biphenylyl group, terphenylyl group, tetrakisphenyl group, styryl Group, naphthyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, pyridyl group, bipyridyl group, triazyl group, pyrimidyl group, quinolyl group, isoquinolyl group, A group such as an aryl group, a pyridoindolyl group, a carbazolyl group, a quinoxalyl group, and a pyrazolyl group, and these substituents may be further substituted, and these substituents are bonded to each other, May be formed.

“Substituted or unsubstituted aromatic hydrocarbons represented by R ₁ to R ₄₇ in the general formula (1) to the general formula (1 ″ ″), the general formula (2), or the general formula (2 ′); "Aromatic hydrocarbon group", "aromatic heterocyclic group" or "fused polycycle" in "group", "substituted or unsubstituted aromatic heterocyclic group" or "substituted or unsubstituted condensed polycyclic aromatic group" As the `` aromatic group '', specifically phenyl group, biphenylyl group, terphenylyl group, tetrakisphenyl group, styryl group, naphthyl group, anthryl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, pyridyl group, Bipyridyl, triazyl, pyrimidyl, furanyl, pyronyl, thienyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, cal Groups such as zolyl, benzoxazolyl, benzothiazolyl, quinoxalyl, benzimidazolyl, pyrazolyl, pyridoindolyl, dibenzofuranyl, dibenzothienyl, naphthyridinyl, phenanthrolinyl, acridinyl Can give.
Here, the “substituted or unsubstituted aromatic heterocyclic group” represented by R ₁ to R ₈ , R ₁₉ to R ₂₇ , R ₄₀ to R ₄₇ is preferably a substituted or unsubstituted pyridyl group, Improvement of injection characteristics can be expected.

A “substituted aromatic hydrocarbon group” represented by R ₁ to R ₄₇ in general formula (1) to general formula (1 ″ ″), general formula (2), or general formula (2 ′); As the “substituent” in the “substituted aromatic heterocyclic group” or “substituted condensed polycyclic aromatic group”, specifically, a deuterium atom, fluorine atom, chlorine atom, cyano group, trifluoromethyl group, nitro group, Straight chain or branched alkyl group having 1 to 6 carbon atoms, cyclopentyl group, cyclohexyl group, straight chain or branched alkoxy group having 1 to 6 carbon atoms, straight chain having 1 to 6 carbon atoms Or a dialkylamino group substituted with a branched alkyl group, phenyl group, biphenylyl group, terphenylyl group, tetrakisphenyl group, styryl group, naphthyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl Group, pyridyl group, bipyridyl group, triazyl group, pyrimidyl group, quinolyl group, isoquinolyl group, indolyl group, pyridoindolyl group, carbazolyl group, quinoxalyl group, pyrazolyl group, and these substituents May be further substituted.

The compound having a substituted bipyridyl group and a triphenylene ring structure represented by the general formula (1) to the general formula (1 ″ ″), the general formula (2), or the general formula (2 ′) of the present invention is novel. This compound has a function of moving electrons faster than conventional electron transport materials, maintaining a stable thin film state, improving luminous efficiency, and lowering driving voltage.
Here, the bipyridyl group bonded to the triphenylene ring (when n1 to n5 are 2 in the general formula (1) or (2)) is a 2,2′-bipyridyl group or a 2,3′-bipyridyl group. Group, 2,4′-bipyridyl group and 3,2′-bipyridyl group are preferable, and 2,2′-bipyridyl group and 2,4′-bipyridyl group are particularly preferable.

The compound having a substituted bipyridyl group and a triphenylene ring structure represented by the general formula (1) to the general formula (1 ″ ″), the general formula (2), or the general formula (2 ′) of the present invention is: It can be used as a constituent material of an electron injection layer and / or an electron transport layer of an organic EL element. By using a material having a higher electron injection / movement speed than conventional materials, the electron transport efficiency from the electron transport layer to the light emitting layer is improved, the light emission efficiency is improved, and the driving voltage is lowered, It has the effect | action that durability of an organic EL element improves.

The compound having a substituted bipyridyl group and a triphenylene ring structure represented by the general formula (1) to the general formula (1 ″ ″), the general formula (2), or the general formula (2 ′) of the present invention is: It can also be used as a constituent material of a light emitting layer of an organic EL element. Compared with conventional materials, the material of the present invention, which has excellent electron transport properties and a wide band gap, is used as a host material for a light emitting layer, and a phosphor or phosphorescent light emitter called a dopant is supported to form a light emitting layer. By using it, the drive voltage is lowered, and an organic EL element with improved luminous efficiency can be realized.

The organic EL device of the present invention uses a compound having a substituted bipyridyl group and a triphenylene ring structure, which has a faster electron movement than a conventional electron transport material and a stable thin film state, and thus has high efficiency and high durability. It became possible to realize.

Since the compound having a substituted bipyridyl group and a triphenylene ring structure of the present invention has a fast electron movement and a stable thin film state, it can be used as a constituent material for an electron injection layer, an electron transport layer, or a light emitting layer of an organic EL device. Useful. An organic EL device manufactured using a compound having a substituted bipyridyl group and a triphenylene ring structure can improve the light emission efficiency and reduce the driving voltage, thereby improving the durability.

1 is a ¹ H-NMR chart of the compound of Example 1 of the present invention (Compound 3). 2 is a ¹ H-NMR chart of the compound of Example 2 of the present invention (Compound 4). FIG. FIG. 3 is a ¹ H-NMR chart of the compound of Example 3 of the present invention (Compound 11). FIG. 3 is a ¹ H-NMR chart of the compound of Example 4 of the present invention (Compound 12). FIG. 6 is a diagram showing EL element configurations of Examples 8 to 11 and Comparative Examples 1 to 5.

The compound having a substituted bipyridyl group and a triphenylene ring structure of the present invention is a novel compound, and these compounds can be synthesized, for example, as follows. First, the corresponding boronate ester form is synthesized by subjecting the corresponding triphenylene compound dihalide to boronic esterification with bis (pinacolato) diboron or the like (see, for example, Non-Patent Document 5), and further, the corresponding boron. A compound having a substituted bipyridyl group and a triphenylene ring structure is obtained by performing a cross-coupling reaction such as Suzuki coupling between an acid ester and a halogenobipyridine having various substituents (see, for example, Non-Patent Document 6). Can be synthesized.
On the other hand, boronic acid ester of bipyridine having various substituents is synthesized by subjecting halogenobipyridine having various substituents to boronic acid esterification with bis (pinacolato) diboron or the like. A compound having a substituted bipyridyl group and a triphenylene ring structure can be synthesized by carrying out a cross-coupling reaction such as Suzuki coupling between a boronic acid ester of bipyridine having a dipyridine and a dihalide of a corresponding triphenylene compound.

Preferred compounds among the compounds having a substituted bipyridyl group and a triphenylene ring structure represented by general formula (1) to general formula (1 ″ ″), general formula (2) or general formula (2 ′) Specific examples of these are shown below, but the present invention is not limited to these compounds.

(Compound 3)

(Compound 4)

(Compound 5)

(Compound 6)

(Compound 7)

(Compound 8)

(Compound 9)

(Compound 10)

(Compound 11)

(Compound 12)

(Compound 13)

(Compound 14)

(Compound 15)

(Compound 16)

(Compound 17)

(Compound 18)

(Compound 19)

(Compound 20)

(Compound 21)

(Compound 22)

(Compound 23)

(Compound 24)

(Compound 25)

(Compound 26)

(Compound 27)

(Compound 28)

(Compound 29)

(Compound 30)

(Compound 31)

(Compound 32)

(Compound 33)

(Compound 34)

(Compound 35)

(Compound 36)

(Compound 37)

(Compound 38)

(Compound 39)

(Compound 40)

(Compound 41)

(Compound 42)

(Compound 43)

(Compound 44)

(Compound 45)

(Compound 46)

(Compound 47)

(Compound 48)

(Compound 49)

(Compound 50)

(Compound 51)

(Compound 52)

(Compound 53)

(Compound 54)

(Compound 55)

These compounds were purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization using a solvent, crystallization method, and the like. The compound was identified by NMR analysis, mass spectrometry, elemental analysis and the like. As physical property values, melting point, glass transition point (Tg) and work function were measured. The melting point is an index of vapor deposition, the glass transition point (Tg) is an index of stability in a thin film state, and the work function is an index of hole blocking ability.

Melting point and glass transition point (Tg) were measured with a high sensitivity differential scanning calorimeter (Bruker AXS, DSC3100S) using powder.

Also, the work function was measured using a photoelectron spectrometer (AC-3, manufactured by Riken Keiki Co., Ltd.) in the atmosphere after forming a 100 nm thin film on the ITO substrate.

As the structure of the organic EL device of the present invention, an anode, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and a cathode are sequentially formed on the substrate, and the anode and the hole transport layer Examples include those having a hole injection layer between them, those having an electron injection layer between the electron transport layer and the cathode, and those having an electron blocking layer between the light emitting layer and the hole transport layer. In these multilayer structures, several organic layers can be omitted. For example, a structure having an anode, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode sequentially on a substrate can be used. .

The light emitting layer, the hole transport layer, and the electron transport layer may have a structure in which two or more layers are laminated.

As the anode of the organic EL element of the present invention, an electrode material having a large work function such as ITO or gold is used. As a hole injection layer of the organic EL device of the present invention, in addition to a porphyrin compound typified by copper phthalocyanine, a starburst type triphenylamine derivative, three or more triphenylamine structures in the molecule, single bond or heteroatom Use of triphenylamine trimers and tetramers such as arylamine compounds having a structure linked by a divalent group not containing an acceptor, acceptor heterocyclic compounds such as hexacyanoazatriphenylene, and coating-type polymer materials Can do. These materials can be formed into a thin film by a known method such as a spin coating method or an ink jet method in addition to a vapor deposition method.

As the hole transport layer of the organic EL device of the present invention, N, N′-diphenyl-N, N′-di (m-tolyl) -benzidine (hereinafter abbreviated as TPD) or N, N′-diphenyl-N , N′-di (α-naphthyl) -benzidine (hereinafter abbreviated as NPD), benzidine derivatives such as N, N, N ′, N′-tetrabiphenylylbenzidine, 1,1-bis [(di-4 -Tolylamino) phenyl] cyclohexane (hereinafter abbreviated as TAPC), various triphenylamine trimers and tetramers, carbazole derivatives, and the like can be used. These may be formed alone, but may be used as a single layer formed by mixing with other materials, layers formed alone, mixed layers formed, or A stacked structure of layers formed by mixing with a layer formed alone may be used. In addition, as a hole injection / transport layer, a coating type such as poly (3,4-ethylenedioxythiophene) (hereinafter abbreviated as PEDOT) / poly (styrene sulfonate) (hereinafter abbreviated as PSS) is used. These polymer materials can be used. These materials can be formed into a thin film by a known method such as a spin coating method or an ink jet method in addition to a vapor deposition method.

In addition, in the hole injection layer or the hole transport layer, a material that is usually used for the layer is further P-doped with trisbromophenylamine hexachloroantimony or the like, or a TPD structure having a partial structure. Molecular compounds and the like can be used.

As an electron blocking layer of the organic EL device of the present invention, 4,4 ′, 4 ″ -tri (N-carbazolyl) triphenylamine (hereinafter abbreviated as TCTA), 9,9-bis [4- (carbazole- 9-yl) phenyl] fluorene, 1,3-bis (carbazol-9-yl) benzene (hereinafter abbreviated as mCP), 2,2-bis (4-carbazol-9-ylphenyl) adamantane (hereinafter Ad) Carbazole derivatives such as 9- [4- (carbazol-9-yl) phenyl] -9- [4- (triphenylsilyl) phenyl] -9H-fluorene And a compound having an electron blocking action such as a compound having a triarylamine structure can be used. These may be formed alone, but may be used as a single layer formed by mixing with other materials, layers formed alone, mixed layers formed, or A stacked structure of layers formed by mixing with a layer formed alone may be used. These materials can be formed into a thin film by a known method such as a spin coating method or an ink jet method in addition to a vapor deposition method.

As the light emitting layer of the organic EL device of the present invention, in addition to the compound having a substituted bipyridyl group and a triphenylene ring structure of the present invention, various metal complexes and anthracene derivatives in addition to metal complexes of quinolinol derivatives including Alq ₃ Bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, polyparaphenylene vinylene derivatives, and the like can be used. In addition, the light emitting layer may be composed of a host material and a dopant material, and in addition to the light emitting material, a thiazole derivative, a benzimidazole derivative, a polydialkylfluorene derivative, or the like can be used as the host material. As the dopant material, quinacridone, coumarin, rubrene, perylene, and derivatives thereof, benzopyran derivatives, rhodamine derivatives, aminostyryl derivatives, and the like can be used. These may be formed alone, but may be used as a single layer formed by mixing with other materials, layers formed alone, mixed layers formed, or A stacked structure of layers formed by mixing with a layer formed alone may be used.

Further, a phosphorescent light emitting material can be used as the light emitting material. As the phosphorescent emitter, a phosphorescent emitter of a metal complex such as iridium or platinum can be used. Green phosphorescent emitters such as Ir (ppy) ₃ , blue phosphorescent emitters such as FIrpic and FIr6, red phosphorescent emitters such as Btp ₂ Ir (acac), and the like are used as host materials. As the hole injecting / transporting host material, carbazole derivatives such as 4,4′-di (N-carbazolyl) biphenyl (hereinafter abbreviated as CBP), TCTA, mCP, and the like can be used. As an electron transporting host material, p-bis (triphenylsilyl) benzene (hereinafter abbreviated as UGH2) and 2,2 ′, 2 ″-(1,3,5-phenylene) -tris (1-phenyl) -1H-benzimidazole) (hereinafter abbreviated as TPBI) and the like can be used.

In order to avoid concentration quenching, it is preferable to dope the phosphorescent light-emitting material into the host material by co-evaporation in the range of 1 to 30 weight percent with respect to the entire light-emitting layer.

These materials can be formed into a thin film by a known method such as a spin coating method or an ink jet method in addition to a vapor deposition method.

As the hole blocking layer of the organic EL device of the present invention, in addition to the compound having a substituted bipyridyl group and a triphenylene ring structure of the present invention, phenanthroline derivatives such as bathocuproin (hereinafter abbreviated as BCP), and quinolinol such as BAlq In addition to derivative metal complexes, various rare earth complexes, oxazole derivatives, triazole derivatives, triazine derivatives, and other compounds having a hole blocking action can be used. These materials may also serve as the material for the electron transport layer. These may be formed alone, but may be used as a single layer formed by mixing with other materials, layers formed alone, mixed layers formed, or A stacked structure of layers formed by mixing with a layer formed alone may be used. These materials can be formed into a thin film by a known method such as a spin coating method or an ink jet method in addition to a vapor deposition method.

As the electron transport layer of the organic EL device of the present invention, in addition to the substituted bipyridyl group and the compound having a triphenylene ring structure of the present invention, in addition to metal complexes of quinolinol derivatives including Alq ₃ and BAlq, various metal complexes, Triazole derivatives, triazine derivatives, oxadiazole derivatives, thiadiazole derivatives, carbodiimide derivatives, quinoxaline derivatives, phenanthroline derivatives, silole derivatives, and the like can be used. These may be formed alone, but may be used as a single layer formed by mixing with other materials, layers formed alone, mixed layers formed, or A stacked structure of layers formed by mixing with a layer formed alone may be used. These materials can be formed into a thin film by a known method such as a spin coating method or an ink jet method in addition to a vapor deposition method.

As an electron injection layer of the organic EL device of the present invention, in addition to the compound having a substituted bipyridyl group and a triphenylene ring structure of the present invention, an alkali metal salt such as lithium fluoride and cesium fluoride, an alkaline earth such as magnesium fluoride Although metal oxides such as metal salts and aluminum oxide can be used, this can be omitted in the preferred selection of the electron transport layer and the cathode.

Furthermore, in the electron injecting layer or the electron transporting layer, a material usually used for the layer and further doped with a metal such as cesium can be used.

As the cathode of the organic EL device of the present invention, an electrode material having a low work function such as aluminum or an alloy having a lower work function such as a magnesium silver alloy, a magnesium indium alloy, or an aluminum magnesium alloy is used as the electrode material.

Hereinafter, embodiments of the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.

<Synthesis of 2,7-bis (2,2′-bipyridin-5-yl) triphenylene (Compound 3)>
Into a reaction vessel purged with nitrogen, 19.5 g of 2,5-dibromopyridine, 150 ml of 2-pyridylzinc bromide, 90 ml of tetrahydrofuran and 4.33 g of tetrakis (triphenylphosphine) palladium (0) were added and cooled. After stirring for an hour, the mixture was further stirred at room temperature for 3 hours. The reaction solution was added to 10% ethylenediaminetetraacetic acid disodium dihydrogen aqueous solution and stirred for 6 hours. Then, 300 ml of chloroform was added, and a liquid separation operation was performed to collect an organic layer. The organic layer was dehydrated with anhydrous magnesium sulfate and concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene) to obtain 11.1 g (yield 63%) of 5-bromo-2,2′-bipyridine as a white powder.

Meanwhile, in a reaction vessel purged with nitrogen, 24.4 g of 1,2-diiodobenzene, 30 g of 3-trimethylsilylphenylboronic acid, 8.8 g of sodium hydroxide, 4.3 g of tetrakis (triphenylphosphine) palladium (0), diethylene glycol The mixture was heated by adding 160 ml of dimethyl ether and 40 ml of water, and stirred at 95 ° C. for 15 hours. After cooling to room temperature, 100 ml of water was added, and the organic layer was collected by performing a liquid separation operation. The organic layer was washed twice with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: n-hexane) and white powder of 3,3 ″ -bis (trimethylsilyl) -1,1 ′: 2 ′, 1 ″ -terphenyl 23.3 g (84% yield) was obtained.

The obtained 3,3 ″ -bis (trimethylsilyl) -1,1 ′: 2 ′, 1 ″ -terphenyl (23 g), bromine (12.6 ml) and chloroform (180 ml) were added to a nitrogen-substituted reaction vessel and cooled. After stirring at 5 ° C. for 3 hours, the mixture was further stirred at room temperature for 4 hours. An organic layer was collected by adding 90 ml of a saturated aqueous sodium sulfite solution and performing a liquid separation operation. The organic layer was washed twice with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by recrystallization using ethanol and then washed with methanol to obtain a white powder of 3,3 ″ -dibromo-1,1 ′: 2 ′, 1 ″ -terphenyl. 4 g (yield 65%) was obtained.

The obtained 3,3 ″ -dibromo-1,1 ′: 2 ′, 1 ″ -terphenyl 12.0 g, molybdenum (V) 16.9 g and dichloromethane 20 ml were added to a nitrogen-substituted reaction vessel, For 19 hours. After adding 100 ml of water to the reaction solution and stirring for 30 minutes, the precipitate was collected by filtration and washed with methanol to obtain a crude product. Chloroform 200 ml, n-hexane 600 ml, and silica gel 36.6 g were added to the crude product, followed by adsorption purification, followed by washing with chloroform to obtain 5.5 g of light yellow powder of 2,7-dibromotriphenylene (yield 46%). Got.

The obtained 2,7-dibromotriphenylene 5.5 g, bis (pinacolato) diboron 7.9 g, potassium acetate 4.2 g, 50 ml of 1,4-dioxane previously dehydrated with molecular sieves 4A, [1,1′-bis ( Diphenylphosphino) ferrocene] palladium (II) dichloride-dichloromethane complex (1: 1) 0.4 g was added to a nitrogen-substituted reaction vessel, heated, and stirred at 80 ° C. for 10 hours. After cooling to 50 ° C., 150 ml of chloroform was added and stirred for 30 minutes. Insoluble materials were removed by filtration, and a crude product was obtained by concentration. The crude product was purified by column chromatography [carrier: silica gel, eluent: ethyl acetate / n-hexane = 1/5 (v / v)], and 2,7-bis (4,4,5,5-tetramethyl There was obtained 4.8 g (yield 70%) of-[1,3,2] dioxaborolan-2-yl) triphenylene white powder.

2.4 g of 2,7-bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolan-2-yl) triphenylene obtained and 5-bromo-2,2′- Add 2.5 g of bipyridine, 7.7 ml of 2M aqueous potassium carbonate solution, 0.3 g of tetrakis (triphenylphosphine) palladium (0), 40 ml of toluene, and 10 ml of ethanol to a nitrogen-substituted reaction vessel, heat and reflux for 9 hours with stirring. did. After cooling to room temperature, the precipitate was collected by filtration. The precipitate was dissolved by adding 2000 ml of chloroform, purified by adsorption by adding 11.5 g of silica gel, and then recrystallized from 1,2-dichlorobenzene to give 2,7-bis (2,2′- 1.6 g (yield 60%) of yellow powder of bipyridin-5-yl) triphenylene (Compound 3) was obtained.

The structure of the obtained yellow powder was identified using NMR. ^The results of ¹ H-NMR measurement are shown in FIG.

Signals were detected following 24 hydrogen ^{_{1 H-NMR (DMSO-d}} 6). δ (ppm) = 9.28 (2H), 9.15 (2H), 9.02-9.03 (2H), 8.93-8.96 (2H), 8.72 (2H), 8. 47-8.56 (6H), 8.14-8.16 (2H), 7.94-7.98 (2H), 7.78-7.79 (2H), 7.43-7.46 ( 2H).

<Synthesis of 2,7-bis (2,2′-bipyridin-6-yl) triphenylene (Compound 4)>
To the reaction vessel purged with nitrogen, 19.5 g of 2,6-dibromopyridine, 150 ml of 2-pyridylzinc bromide, 90 ml of tetrahydrofuran and 4.33 g of tetrakis (triphenylphosphine) palladium (0) were added and cooled. After stirring for an hour, the mixture was further stirred at room temperature for 3 hours. The reaction solution was added to a 10% disodium dihydrogen tetraacetate aqueous solution and stirred for 6 hours, and then 300 ml of chloroform was added and the organic layer was collected by performing a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene) to obtain 11.1 g (yield 63%) of 6-bromo-2,2′-bipyridine as a white powder.

2.4 g of 6-bromo-2,2′-bipyridine obtained and 2,7-bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolane-2 synthesized in Example 1 -Yl) 2.3 g of triphenylene, 7.4 ml of 2M aqueous potassium carbonate solution, 0.3 g of tetrakis (triphenylphosphine) palladium (0), 40 ml of toluene, and 10 ml of ethanol were added to a nitrogen-substituted reaction vessel and heated while stirring. Refluxed for 9 hours. After cooling to room temperature, the precipitate was collected by filtration. To the precipitate was added 1300 ml of chloroform, the insoluble matter was removed by filtration, and then purified by recrystallization from 1,2-dichlorobenzene to obtain 2,7-bis (2,2′-bipyridin-6-yl) triphenylene (compound 4 g of light yellowish white powder 4) (yield 66%) was obtained.

The structure of the obtained pale yellowish white powder was identified using NMR. ^The results of ¹ H-NMR measurement are shown in FIG.

^The following 24 hydrogen signals were detected by ¹ H-NMR (DMSO-d ₆ ). δ (ppm) = 9.50 (2H), 8.92-8.98 (4H), 8.64-8.70 (4H), 8.54-8.57 (2H), 8.38-8 .40 (2H), 8.28-8.30 (2H), 8.06-8.10 (2H), 7.98-8.01 (2H), 7.78-7.80 (2H), 7.43-7.45 (2H).

<Synthesis of 2,11-bis (2,2′-bipyridin-5-yl) triphenylene (Compound 11)>
In a reaction vessel purged with nitrogen, 10 g of 1,2-dibromobenzene, 23.7 g of bis (pinacolato) diboron, 12.5 g of potassium acetate, 150 ml of 1,4-dioxane previously dehydrated with molecular sieves 4A, [1,1′- Bis (diphenylphosphino) ferrocene] palladium (II) dichloride-dichloromethane complex (1: 1) 1.0 g was added to a nitrogen-substituted reaction vessel, heated, and stirred at 80 ° C. for 10 hours. After cooling to 50 ° C., 150 ml of chloroform was added and stirred for 30 minutes. Insoluble materials were removed by filtration, and a crude product was obtained by concentration. The crude product was purified by column chromatography [carrier: silica gel, eluent: ethyl acetate / n-hexane = 1/4 (v / v)], and 1,2-bis (4,4,5,5-tetramethyl There was obtained 7.2 g (yield 54%) of a white powder of-[1,3,2] dioxaborolan-2-yl) benzene.

On the other hand, 30 g of 3,3′-dimethoxy-1,1′-biphenyl, 15.8 ml of bromine and 250 ml of acetic acid were added to a nitrogen-substituted reaction vessel and stirred at room temperature for 2 hours. After adding 90 ml of a saturated aqueous sodium sulfite solution to the reaction solution, 200 ml of chloroform was added, and a liquid separation operation was performed to collect an organic layer. The organic layer was washed twice with 100 ml of water, dried over anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was washed with ethanol to obtain 36.3 g (yield 70%) of 2,2'-dibromo-3,3'-dimethoxy-1,1'-biphenyl white powder.

The obtained 2,2′-dibromo-3,3′-dimethoxy-1,1′-biphenyl 2.8 g and the 1,2-bis (4,4,5,5-tetramethyl- [1, 3,2] dioxaborolan-2-yl) benzene (3.0 g), potassium phosphate (9.6 g), tetrakis (triphenylphosphine) palladium (0) (0.43 g), tetrahydrofuran (50 ml) and water (15 ml) were added to a nitrogen-substituted reaction vessel. Heated and stirred at 60 ° C. for 48 hours. After cooling to room temperature, 100 ml of chloroform was added, and a liquid separation operation was performed to collect an organic layer. The organic layer was washed twice with 50 ml of water, dried over anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography [carrier: silica gel, eluent: ethyl acetate / n-hexane / methylene chloride = 1/10/1 (v / v / v)], and then washed with methanol to obtain 2 Thus, 1.72 g (65.6%) of white powder of 11-dimethoxytriphenylene was obtained.

The obtained 2,11-dimethoxytriphenylene (1.5 g), boron tribromide: dichloromethane solution (1 mol / L) (10.9 ml) and dichloromethane (50 ml) were purged with nitrogen, added to a reaction vessel cooled to −78 ° C., and warmed to room temperature. After warming, the mixture was stirred for 20 hours. 50 ml of water was added to the reaction solution and stirred for 30 minutes, and then the precipitate was collected by filtration. The precipitate was washed with methanol to obtain 1.25 g (yield 93%) of a white powder of triphenylene-2,11-diol.

1.25 g of the obtained triphenylene-2,11-diol, 6.87 g of N-phenyl-bis (trifluoromethanesulfonimide), 5.1 g of sodium carbonate, and 50 ml of dimethylformamide were added to a nitrogen-substituted reaction vessel, and the mixture was stirred at room temperature. Stir for hours. After adding 50 ml of water to the reaction solution and stirring for 30 minutes, the precipitate was collected by filtration. The precipitate was washed with methanol to obtain 2.38 g (yield 91%) of white powder of triphenylene-2,11-diyl-bis (trifluoromethanesulfonate).

2.3 g of the obtained triphenylene-2,11-diyl-bis (trifluoromethanesulfonate), 2.5 g of bis (pinacolato) diboron, 1.3 g of potassium acetate, 50 ml of 1,4-dioxane previously dehydrated with molecular sieves 4A, 0.1 g of [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride-dichloromethane complex (1: 1) was added to a nitrogen-substituted reaction vessel, heated, and stirred at 80 ° C. for 10 hours. After cooling to 50 ° C., 150 ml of chloroform was added and stirred for 30 minutes. Insoluble materials were removed by filtration, and the filtrate was concentrated to obtain a crude product. The crude product was purified by column chromatography [carrier: silica gel, eluent: ethyl acetate / n-hexane = 1/5 (v / v)], and 2,11-bis (4,4,5,5-tetramethyl). There were obtained 1.1 g (yield 52%) of a white powder of-[1,3,2] dioxaborolan-2-yl) triphenylene.

0.9 g of the obtained 2,11-bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolan-2-yl) triphenylene, 5-bromo-2 synthesized in Example 1, 2'-bipyridine 0.9 g, 2 M aqueous potassium carbonate solution 2.9 ml, tetrakis (triphenylphosphine) palladium (0) 0.1 g, toluene 40 ml, ethanol 10 ml were added to a nitrogen-substituted reaction vessel and heated with stirring. Refluxed for 9 hours. After cooling to room temperature, the precipitate was collected by filtration. The precipitate was dissolved by adding 1000 ml of chloroform, purified by adsorption by adding 11.5 g of silica gel, and then recrystallized from 1,2-dichlorobenzene to give 2,11-bis (2,2 ′ There was obtained 0.7 g (yield 70%) of a yellow powder of -bipyridin-5-yl) triphenylene (Compound 11).

^The following 24 hydrogen signals were detected by ¹ H-NMR (DMSO-d ₆ ). δ (ppm) = 9.41 (2H), 9.37 (2H), 9.95 (2H), 8.88-8.85 (2H), 8.71 (2H), 8.60-8. 57 (2H), 8.56-8.54 (2H), 8.52-8.45 (2H), 8.16 (2H), 7.95-7.98 (2H), 7.74 (2H) ), 7.45 (2H).

<Synthesis of 2,11-bis (2,2′-bipyridin-6-yl) triphenylene (Compound 12)>
0.8 g of 2,11-bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolan-2-yl) triphenylene synthesized in Example 3 and 6-bromo synthesized in Example 2 -2,2′-bipyridine 0.8 g, 2.3 ml of 2M potassium carbonate aqueous solution, 0.1 g of tetrakis (triphenylphosphine) palladium (0), 40 ml of toluene, and 10 ml of ethanol were added to a nitrogen-substituted reaction vessel and heated. The mixture was refluxed for 9 hours with stirring. After cooling to room temperature, the precipitate was collected by filtration. To the precipitate was added 1300 ml of chloroform, the insoluble matter was removed by filtration, and then purified by recrystallization with 1,2-dichlorobenzene to obtain 2,11-bis (2,2′-bipyridin-6-yl) triphenylene (compound 0.6 g (yield 71%) of 12) was obtained.

The structure of the obtained pale yellowish white powder was identified using NMR. The the ¹ H-NMR measurement results are shown in FIG.

^The following 24 hydrogen signals were detected by ¹ H-NMR (DMSO-d ₆ ). δ (ppm) = 9.74 (2H), 8.98 (2H), 8.90-8.87 (2H), 8.70 (2H), 8.66-8.62 (4H), 8. 48 (2H), 8.41 (2H), 8.17-8.13 (2H), 7.79-7.75 (4H), 7.43-7.40 (2H).

<Synthesis of 2,7-di ([2,4′-bipyridin] -5-yl) triphenylene (Compound 55)>
In a reaction vessel purged with nitrogen, 9.6 g of 2,5-dibromopyridine, 2.5 g of 4-pyridineboronic acid, 50 ml of toluene, 40 ml of ethanol, 15.2 ml of 2M aqueous potassium carbonate solution, tetrakis (triphenylphosphine) palladium (0) 1.50 g was added, heated, and refluxed for 24 hours with stirring. After cooling to room temperature, 500 ml of chloroform and 300 ml of water were added, and the organic layer was collected by performing a liquid separation operation. The organic layer was washed twice with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography [carrier: silica gel, eluent: toluene: ethyl acetate = 1: 1 (v / v)] to obtain 3.3 g of white powder of 5-bromo-2,4′-bipyridine (yield). Yield 69%).

Obtained 2.4 g of 5-bromo-2,4′-bipyridine and 2,7-bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolane-synthesized in Example 1) 2-yl) triphenylene 2.0 g, 2 M aqueous potassium carbonate solution 6.3 ml, tetrakis (triphenylphosphine) palladium (0) 0.3 g, toluene 40 ml, and ethanol 25 ml were added to a nitrogen-substituted reaction vessel and heated and stirred. The mixture was refluxed for 24 hours. After cooling to room temperature, the precipitate was collected by filtration. To the precipitate was added 1300 ml of chloroform, the insoluble matter was removed by filtration, and then purified by recrystallization from 1,2-dichlorobenzene to obtain 2,7-di ([2,4′-bipyridin] -5-yl) triphenylene. 1.1 g (yield 50%) of pale yellowish white powder of (Compound 55) was obtained.

Using the matrix-assisted laser desorption / ionization time-of-flight mass spectrometer (AXIMA-CFR Plus, manufactured by Shimadzu Corp.) and elemental analyzer (Yanaco CHN coder MT-5 model manufactured by Yanagimoto Seisakusho) The structure was identified.

MS (m / z) 537 [calculated value (m / z) 536.20],
Elemental analysis, measured value: C; 85.08, H; 4.42 , N; 10.39, calcd _{_{_{(C 38 H 24 N 4)}}} : C; 85.05, H; 4.51, N; 10 .44.

[Comparative Synthesis Example 1]
<Synthesis of 3,3 ″ -bis (2,2′-bipyridin-5-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl (Comparative Compound 1)>

3,3 ″ -Dibromo-1,1 ′: 2 ′, 1 ″ -terphenyl synthesized in Example 1 5.0 g, bis (pinacolato) diboron 6.9 g, potassium acetate 3.8 g, molecular sieves in advance Add 50 ml of 1,4-dioxane dehydrated with 4A and 0.3 g of [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride-dichloromethane complex (1: 1) to a nitrogen-substituted reaction vessel. Heated and stirred at 80 ° C. for 11 hours. After cooling to 50 ° C., 100 ml of chloroform was added and stirred for 30 minutes. Insoluble materials were removed by filtration, and a crude product was obtained by concentration. The crude product was purified by column chromatography [carrier: silica gel, eluent: ethyl acetate / n-hexane = 1/20 (v / v), and 3,3 ″ -bis (4,4,5,5-tetra Methyl- [1,3,2] dioxaborolan-2-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl white powder 3.8 g (yield 61%) was obtained.

The resulting 3,3 ″ -bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolan-2-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl 1.8 g, 1.8 g of 5-bromo-2,2′-bipyridine synthesized in Example 1, 5.8 ml of 2M aqueous potassium carbonate solution, 0.2 g of tetrakis (triphenylphosphine) palladium (0), 40 ml of toluene, ethanol 10 ml was added to a reaction vessel purged with nitrogen, heated, and refluxed for 20 hours with stirring. After cooling to room temperature, 30 ml of water and 100 ml of chloroform were added, and a liquid separation operation was performed to collect an organic layer. The organic layer was washed with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography [carrier: NH silica gel, eluent: ethyl acetate / n-hexane = 1/5 (v / v)], and 3,3 ″ -bis (2,2 A white powder of 1.5 g (yield 80%) of “-bipyridin-5-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl (Comparative Compound 1) was obtained.

(Comparative Compound 1)

The structure of the resulting white powder was identified using NMR.
^The following 26 hydrogen signals were detected by ¹ H-NMR (CDCl ₃ ). δ (ppm) = 8.65-8.66 (2H), 8.51-8.53 (2H), 8.31-8.33 (2H), 8.08 (2H), 7.99-8 .01 (2H), 7.71-7.79 (4H), 7.59-7.61 (2H), 7.54-7.56 (2H), 7.50-7.52 (2H), 7.34-7.38 (2H), 7.25-7.28 (4H).

[Comparative Synthesis Example 2]
<Synthesis of 3,3 ″ -bis (2,2′-bipyridin-6-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl (Comparative Compound 2)>

3,3 ″ -bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolan-2-yl) -1,1 ′ synthesized in Comparative Synthesis Example 1, 2 ′, 1 ′ 1.8 g of '-terphenyl, 1.8 g of 6-bromo-2,2'-bipyridine synthesized in Example 2, 5.8 ml of 2M aqueous potassium carbonate solution, 0.2 g of tetrakis (triphenylphosphine) palladium (0), Toluene 40 ml and ethanol 10 ml were added to a nitrogen-substituted reaction vessel, heated, and refluxed for 8 hours with stirring. After cooling to room temperature, 30 ml of water and 40 ml of toluene were added, and a liquid separation operation was performed to collect an organic layer. The organic layer was washed with 30 ml of water, dried over anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography [carrier: NH silica gel, eluent: ethyl acetate / n-hexane = 1/5 (v / v)], and 3,3 ″ -bis (2,2 1.5 g (yield 75%) of white powder of “-bipyridin-6-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl (Comparative Compound 2) was obtained.

(Comparative Compound 2)

The structure of the resulting white powder was identified using NMR.
^The following 26 hydrogen signals were detected by ¹ H-NMR (CDCl 3). δ (ppm) = 8.66-8.68 (4H), 8.35-8.40 (4H), 7.79-7.83 (2H), 7.69-7.72 (2H), 7 .45-7.58 (8H), 7.35-7.39 (4H), 7.28-7.31 (2H).

[Comparative Synthesis Example 3]
<Synthesis of 4,4 ″ -bis (2,2′-bipyridin-6-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl (Comparative Compound 3)>

In a reaction vessel purged with nitrogen, 20 g of 1,2-diiodobenzene, 25 g of 4-trimethylsilylphenylboronic acid, 7.4 g of sodium hydroxide, 3.6 g of tetrakis (triphenylphosphine) palladium (0), 240 ml of diethylene glycol dimethyl ether, water 60 ml was added and heated, followed by stirring at 95 ° C. for 15 hours. After cooling to room temperature, 100 ml of water was added, and the organic layer was collected by performing a liquid separation operation. The organic layer was washed twice with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: n-hexane), and white powder of 4,4 ″ -bis (trimethylsilyl) -1,1 ′: 2 ′, 1 ″ -terphenyl 21.1 g (yield 93%) was obtained.

The obtained 4,4 ″ -bis (trimethylsilyl) -1,1 ′: 2 ′, 1 ″ -terphenyl (21 g), bromine (11.5 ml) and chloroform (150 ml) were added to a nitrogen-substituted reaction vessel and cooled. After stirring at 5 ° C. for 3 hours, the mixture was further stirred at room temperature for 4 hours. An organic layer was collected by adding 90 ml of a saturated aqueous sodium sulfite solution and performing a liquid separation operation. The organic layer was washed twice with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by recrystallization using ethanol and then washed with methanol to obtain a white powder of 4,4 ″ -dibromo-1,1 ′: 2 ′, 1 ″ -terphenyl. 9 g (68% yield) was obtained.

The resulting 4,4 ″ -dibromo-1,1 ′: 2 ′, 1 ″ -terphenyl 5.0 g, bis (pinacolato) diboron 7.2 g, potassium acetate 3.8 g, dehydrated in advance with Molecular Sieves 4A 1,4-dioxane 50 ml, [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride-dichloromethane complex (1: 1) 0.3 g was added to a nitrogen-substituted reaction vessel and heated. Stir at 80 ° C. for 10 hours. After cooling to 50 ° C., 150 ml of chloroform was added and stirred for 30 minutes. Insoluble materials were removed by filtration, and a crude product was obtained by concentration. The crude product was purified by column chromatography [carrier: silica gel, eluent: ethyl acetate / n-hexane = 1/5 (v / v)], and 4,4 ″ -bis (4,4,5,5- Tetramethyl- [1,3,2] dioxaborolan-2-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl white powder (3.5 g, yield 56%) was obtained.

The resulting 4,4 ″ -bis (4,4,5,5-tetramethyl- [1,3,2] dioxaborolan-2-yl) -1,1 ′: 2 ′, 1 ″ -terphenyl 2.0 g, 2.0 g of 6-bromo-2,2′-bipyridine synthesized in Example 2, 6.0 ml of 2M aqueous potassium carbonate solution, 0.2 g of tetrakis (triphenylphosphine) palladium (0), 32 ml of toluene, ethanol 8 ml was added to a reaction vessel purged with nitrogen, heated, and refluxed for 9 hours with stirring. After cooling to room temperature, 100 ml of water was added, and the organic layer was collected by performing a liquid separation operation. The organic layer was washed twice with 100 ml of water, dehydrated with anhydrous magnesium sulfate, and concentrated to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: chloroform), and then recrystallized with toluene to obtain 4,4 ″ -bis (2,2′-bipyridine-6) having the following structural formula. -Ill) -1,1 ′: 2 ′, 1 ″ -terphenyl (Comparative Compound 3) 1.6 g (yield 74%) of white powder was obtained.

(Comparative Compound 3)

The structure of the resulting white powder was identified using NMR.
Signals were detected following 26 hydrogen ^{_{1 H-NMR (CDCl 3)}} . δ (ppm) = 8.67 (2H), 8.60 (2H), 8.33 (2H), 8.06 (4H), 7.78-7.86 (4H), 7.74 (2H) 7.53-7.48 (4H), 7.36 (4H), 7.30-7.28 (2H).

About the compound of this invention, melting | fusing point and the glass transition point were calculated | required with the highly sensitive differential scanning calorimeter (The product made from Bruker AXS, DSC3100S).
Melting point Glass transition point Compound of Invention Example 1 338 ° C None Compound of Invention Example 2 285 ° C None

The glass transition point of the compound of the present invention was not observed. This indicates that the thin film state is stable in the compound of the present invention.

Using the compound of the present invention, a 50 nm-thick deposited film was formed on an ITO substrate, and the work function was measured with an atmospheric photoelectron spectrometer (AC-3 type, manufactured by Riken Keiki).
Work Function Compound of Invention Example 1 5.74 eV
Compound of Example 2 of the present invention 5.69 eV
Inventive Example 3 compound 5.82 eV
Inventive Example 4 compound 5.73 eV
Inventive Example 5 Compound 6.21 eV

Thus, the compound of the present invention has a value deeper than the work function 5.4 eV of a general hole transport material such as NPD or TPD, and has a large hole blocking ability.

As shown in FIG. 5, the organic EL element has a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and an electron injection layer 6 on a glass substrate 1 on which an ITO electrode is previously formed as a transparent anode 2. The cathode (silver electrode) 7 was deposited in this order.

Specifically, the glass substrate 1 on which ITO having a thickness of 100 nm was formed was washed with an organic solvent, and then the surface was washed by UV ozone treatment. Then, this glass substrate with an ITO electrode was mounted in a vacuum vapor deposition machine and the pressure was reduced to 0.001 Pa or less. Subsequently, NPD was formed as a hole transport layer 3 so as to cover the transparent anode 2 so as to have a film thickness of 50 nm at a deposition rate of 2 Å / s. On this hole transport layer 3, Alq ₃ was formed as a light emitting layer 4 so as to have a film thickness of 20 nm at a deposition rate of 2 Å / s. On this light emitting layer 4, the compound of Example 1 of the present invention (Compound 3) was formed as an electron transport layer 5 so as to have a film thickness of 30 nm at a deposition rate of 2 Å / s. On the electron transport layer 5, a magnesium silver alloy was formed as the electron injection layer 6 so as to have a film thickness of 100 nm at a deposition rate of 3.3 Å / s. Finally, silver was deposited to a thickness of 10 nm to form the cathode 7. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere.

The measurement results of the light emission characteristics when a DC voltage was applied to the organic EL device produced using the compound of Example 1 of the present invention (Compound 3) are shown in Table 1.

Example An organic EL device was produced under the same conditions as in Example 8 by replacing the material of the electron transport layer 5 in Example 8 with the compound of Example 3 of the present invention (Compound 11). About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 1 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

Example An organic EL device was produced under the same conditions as in Example 8 by replacing the material of the electron transport layer 5 in Example 8 with the compound of Example 5 of the present invention (Compound 55). About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 1 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

[Comparative Example 1]
For comparison, instead of the material of the electron transport layer 5 in Example 8 to Alq _3, to produce an organic EL element under the same conditions as in Example 8. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 1 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

[Comparative Example 2]
For comparison, an organic EL device was produced under the same conditions as in Example 8 by replacing the material of the electron transport layer 5 in Example 8 with the comparative compound 1. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 1 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

[Comparative Example 3]
For comparison, an organic EL device was produced under the same conditions as in Example 8 by replacing the material of the electron transport layer 5 in Example 8 with the comparative compound 2. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 1 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

[Comparative Example 4]
For comparison, an organic EL device was produced under the same conditions as in Example 8 by replacing the material of the electron transport layer 5 in Example 8 with the comparative compound 3. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 1 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

As shown in Table 1, the driving voltage at a current density of 10 mA / cm ² was 5.70 V of Comparative Example 1 using Alq _3, and 6.2 of Comparative Examples 2 to 4 using Comparative Compound 1 to Comparative Compound 3. Compared to 60 V to 7.50 V, the voltage was greatly reduced to 4.10 V in Example 8, 4.40 V in Example 9, and 4.60 V in Example 10. Furthermore, all of the luminance, light emission efficiency, and power efficiency at a current density of 10 mA / cm ² were greatly improved.

After the glass substrate 1 on which the ITO film having a thickness of 100 nm was formed was washed with an organic solvent, the surface was washed by UV ozone treatment. Then, this glass substrate with an ITO electrode was mounted in a vacuum vapor deposition machine and the pressure was reduced to 0.001 Pa or less. Subsequently, NPD was formed as a hole transport layer 3 so as to cover the transparent anode 2 so as to have a film thickness of 60 nm at a deposition rate of 2 Å / s. On this hole transport layer 3, 2- (tert-butyl) -9,10-diphenylanthracene (TBADN) and blue fluorescent light emitter DPAVB are formed as the light emitting layer 4, and the deposition rate ratio is TBADN: DPAVB = 95: 5. Binary vapor deposition was performed at a vapor deposition rate of and a film thickness of 30 nm was formed. On this light emitting layer 4, the compound of Example 1 of the present invention (Compound 3) was formed as an electron transport layer 5 so as to have a film thickness of 30 nm at a deposition rate of 2 Å / s. On the electron transport layer 5, a magnesium silver alloy was formed as the electron injection layer 6 so as to have a film thickness of 100 nm at a deposition rate of 3.3 Å / s. Finally, silver was deposited to a thickness of 10 nm to form the cathode 7. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere.

Table 2 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the organic EL device produced using the compound of Example 1 (Compound 3) of the present invention.

[Comparative Example 5]
For comparison, instead of the material of the electron transport layer 5 in Example 11 to Alq _3, to produce an organic EL element under the same conditions as in Example 11. About the produced organic EL element, the characteristic measurement was performed at normal temperature in air | atmosphere. Table 2 summarizes the measurement results of the light emission characteristics when a DC voltage was applied to the produced organic EL element.

As shown in Table 2, the driving voltage at a current density of 10 mA / cm ² was greatly reduced to 4.80 V in Example 11 compared to 8.80 V in Comparative Example 5 using Alq ₃ . Furthermore, all of the power efficiency at a current density of 10 mA / cm ² was greatly improved.

As it is clear from these results, the organic EL device using a compound having a bipyridyl group and a triphenylene ring structure of the present invention, typical electron transport is used as a material Alq _3, and the central skeleton nonplanar structure It was found that a large improvement in power efficiency and a significant reduction in practical driving voltage can be achieved as compared with the devices using Comparative Compounds 1 to 3 as described above.

Thus, from the remarkable decrease in driving voltage in the organic EL device using the compound having bipyridyl group and triphenylene ring structure of the present invention, the speed of electron transfer of the compound having bipyridyl group and triphenylene ring structure of the present invention is generally It is expected to be faster at each stage than Alq ₃ which is a typical electron transport material.

The compound having a bipyridyl group and a triphenylene ring structure of the present invention is excellent as a compound for an organic EL device because it has good electron injection / transport performance and a stable thin film state. By producing an organic EL element using the compound, high efficiency can be obtained, practical driving voltage can be lowered, and durability can be improved. For example, it has become possible to develop home appliances and lighting.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Transparent anode 3 Hole transport layer 4 Light emitting layer 5 Electron transport layer 6 Electron injection layer 7 Cathode

Claims

A compound having a substituted bipyridyl group and a triphenylene ring structure, represented by the following general formula (1) or (2).

(1)
(Wherein R 1 to R 18 may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or an optionally substituted carbon atom) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n1 and n2 may be the same or different and each represents 2 or 3. Here, a plurality of R 3 to R 8 may be the same or different from each other.

(2)
(Wherein R 19 to R 39 may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or a carbon atom which may have a substituent) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n3, n4 and n5 may be the same or different and each represents 2 or 3. Here, a plurality of R 22 to R 30 may be the same or different from each other.
The compound having a substituted bipyridyl group and a triphenylene ring structure according to claim 1 represented by the following general formula (1 ').

(1 ')
(Wherein, R 1 ~ R 18, which may hydrogen atom be the same or different, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, optionally carbon atoms which may have a substituent 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n1 and n2 may be the same or different and each represents 2 or 3. Here, a plurality of R 3 to R 8 may be the same or different from each other.
The compound having a substituted bipyridyl group and a triphenylene ring structure according to claim 1 represented by the following general formula (1 '').

(1 '')
(Wherein R 1 to R 18 may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or an optionally substituted carbon atom) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n1 and n2 may be the same or different and each represents 2 or 3. Here, a plurality of R 3 to R 8 may be the same or different from each other.
The compound having a substituted bipyridyl group and a triphenylene ring structure represented by the following general formula (1 ''').

(1 ''')
(In the formula, R 3 to R 18 and R 40 to R 47 may be the same or different and have a hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, trifluoromethyl group, or substituent. A linear or branched alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycycle Represents an aromatic group.)
The compound having a substituted bipyridyl group and a triphenylene ring structure represented by the following general formula (1 '''').

(1 '''')
(In the formula, R 3 to R 18 and R 40 to R 47 may be the same or different and have a hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, trifluoromethyl group, or substituent. A linear or branched alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycycle Represents an aromatic group.)
The compound having a substituted bipyridyl group and a triphenylene ring structure according to claim 1, which is represented by the following general formula (2 ').

(2 ')
(Wherein R 19 to R 39 may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or a carbon atom which may have a substituent) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n3, n4 and n5 may be the same or different and each represents 2 or 3. Here, a plurality of R 22 to R 30 may be the same or different from each other.
In an organic electroluminescence device having a pair of electrodes and at least one organic layer sandwiched therebetween, a compound having a substituted bipyridyl group and a triphenylene ring structure represented by the following general formula (1) or (2): An organic electroluminescence device characterized in that it is used as a constituent material of at least one organic layer.

(1)
(Wherein R 1 to R 18 may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or an optionally substituted carbon atom) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n1 and n2 may be the same or different and each represents 2 or 3. Here, a plurality of R 3 to R 8 may be the same or different from each other.

(2)
(Wherein R 19 to R 39 may be the same or different and each represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, or a carbon atom which may have a substituent) 1 to 6 linear or branched alkyl groups, substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups, n3, n4 and n5 may be the same or different and each represents 2 or 3. Here, a plurality of R 22 to R 30 may be the same or different from each other.
The organic layer is an electron transport layer, and the compound represented by the general formula (1) or (2) is used as at least one constituent material in the electron transport layer. The organic electroluminescent element according to claim 7.
The organic layer is an electron injection layer, and the compound represented by the general formula (1) or (2) is used as at least one constituent material in the electron injection layer. The organic electroluminescent element according to claim 7.
The organic layer is a light emitting layer, and the compound represented by the general formula (1) or (2) is used as at least one constituent material in the light emitting layer. 8. The organic electroluminescence device according to 7.